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Shrink–swell is the volume change that occurs as a result of changes in the moisture content of clay-rich soils. Swelling pressures can cause heave, or lifting of structures, whilst shrinkage can cause settlement or subsidence, which may be differential.
Why is shrink swell important?
Shrink/swell potential is the relative change in volume to be expected with changes in moisture content, that is, the extent to which the soil shrinks as it dries out or swells when it gets wet. Shrinking and swelling of soils causes much damage to building foundations, roads and other structures.
What causes soil shrinkage?
The soil shrinkage is defined as the specific volume change of soil relative to its water content and is mainly due to clay swelling properties (Haines, 1923; Stirk, 1954). Shrinkage is due to the volume change of the soil plasma and to some extent of the structural porosity with water content.
What causes swelling soils to swell?
Swelling soils, also known as expansive soils, are ones that swell in volume when subjected to moisture. These swelling soils typically contain clay minerals that attract and absorb water. As more water is absorbed, the plates are forced further apart, leading to an increase in soil pore pressure (Handy, 1995).
How compaction is affecting swelling and compressibility of soil?
The swelling pressure increases as the voids are filled. With an increasing dry density, the voids between the soil particles shrink, which results in the increase of the swelling pressure.
How do you stop clay from swelling?
This may occur, because clays are normally saturated with brine water and not with fresh water. This swelling can be prevented with the injection of some additive, for example, sodium chloride, potassium chloride, calcium chloride, or an alcohol or a similar organic material [70].
Is shrink a swell?
Shrink–swell is the volume change that occurs as a result of changes in the moisture content of clay-rich soils. Swelling pressures can cause heave, or lifting of structures, whilst shrinkage can cause settlement or subsidence, which may be differential.
How do you reduce soil swelling?
Chemical admixtures have been used to alter the characteristics of clay mineral and reduce its potential for swelling. Lime is perhaps the most effective of all the chemicals used to stabilize the expansive soils.
Which soil separate is most susceptible to swelling and shrinking?
Clay soil has a high shrink-swell capacity. As the particles shrink they separate and cause cracks, from whisper thin to an inch or more. The more cracks and wider the cracks, the greater the shrink-swell capacity of the soil, which translates to a higher clay content.
What causes clay swelling?
Clay swelling occurs when water-base filtrates from drilling, completion, workover or stimulation fluids enter the formation. Clay swelling can be caused by ion exchange or changes in salinity. In some cases, brines such as potassium chloride [KCl] are used in completion or workover operations to avoid clay swelling.
What to do about swelling?
Mild swelling Rest and protect a sore area. Elevate the injured or sore area on pillows while applying ice and any time you are sitting or lying down. Avoid sitting or standing without moving for prolonged periods of time. A low-sodium diet may help reduce swelling.
What is a high shrink swell index?
The shrink–swell index of clay refers to the extent certain clay minerals will expand when wet and retract when dry. Soil with a high shrink–swell capacity is problematic and is known as shrink–swell soil, or expansive soil.
How do you find the swelling of soil?
Calculating the percentage change in height from the wet soil to the dry will give you a measure of the swell factor of the soil. For example, if the dry soil was 1 inch high and the wet soil is 1.54 inches high, divide 1 by 1.54 and multiply by 100 to get a 65 percent swell factor.
What are the factors affecting swelling potential?
The Swelling potential of the expansive soil mainly depends upon the properties of soil and environmental factors,and stress conditions. Swelling pressure is a key parameter used in designing structures in and on expansive soil.
Which soil will swell more on wetting?
When the water content of expansive clay changes due to drying or wetting, it leads to changes in the volume and void ratio of the soil. When a sample of dry expansive clay is wetted, the increase in water content will cause an increase in the volume of voids (i.e. swelling).
Which is more compressible clay or sand?
Gravels and sands are practically incompressible. If a moist mass of these materials is subjected to compression, there is no significant change in their volume; Clays are compressible.
Which clay mineral gives maximum swelling?
1) Illite consists of the basic montmorillonite units but is bonded by potassium ions. 2) This mineral is very stable and does not swell or shrinks largely. 1) This bonding is very weak, and water can enter easily. 2) Thus, this mineral can imbibe a large quantity of water causing swelling.
What is clay stabilizer?
A chemical additive used in stimulation treatments to prevent the migration or swelling of clay particles in reaction to water-base fluid. Clay stabilizers act to retain the clay platelets in position by controlling the charge and electrolytic characteristics of the treatment fluid.
Is chlorite a swelling clay?
In lower exchange capacity clays such as kaolinite, illite and chlorite, hydration does not cause swelling but can generate sufficient osmotic pressure to cause separation of individual clay platelets which, under the influence of flowing liquid, are dispersed into the pore network.
How can you help avoid Foundation issues due to shrink swell soil?
One of the easiest ways to protect your foundation from shrink swell soil is to make sure that your drainage system is in good working order. Clear your gutters. Point the downspouts away from your home. Extend downspouts – if possible – at least 5 feet away from your home.
What is a shrink swell test?
The shrink swell test is a simple test that is routinely employed in Australian geotechnical engineering practice to assess quantita- tively the expansive potential of undisturbed or remolded clay soils, and to guide design of footings on these soils.
How does wood shrink and swell?
Shrinking and swelling occur as the wood changes moisture content in response to daily as well as seasonal changes in the relative humidity of the atmosphere, i.e., when the air is humid, wood adsorbs moisture and swells; when the air is dry, wood loses moisture and shrinks.
